Fire alarm system



March 11, 1952 J. D. CONSTANTINO FIRE ALARM SYSTEM Filed Jan. 22, 1948 2 SI-IEETS-Sl-IEET l [Evade 7' 7 1; WS-

March 11, 1952 J. D. CONSTANTINO ,5

r FIRE ALARM SYSTEM Filed Jan. 22, 1948 2 SHEETS-SHEET 2 r v a l-FL zz y/ Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE 1 Claim.

Notwithstanding modern methods and improvements in fire protection and prevention, fires still cause great loss of life and property. Because of lack of knowledge andthe expense the periodic fire inspections and drills, sprinkler systems and alarm systems which have reduced fire losses in large commercial establishments are seldom used in homes, small hotels and business establishments whose integrated losses, resulting from a great number of small fires, account for a major portion of the total fire loss. Much of such loss could be prevented by the prompt discovery and control of these small fires before too much damage can be caused.

Although a fire alarm system is admirably adapted to perform this function the use thereof in homes and small establishments has not been extensive. The reliable systems which have been available are complicated, expensive and require constant maintenance. Simple and inexpensive systems are often unreliable, either turning in false alarms or failing to indicate a fire at a crucial moment. Another common fault is the necessity of periodic testing to make certain that these systems are operable.

The objects of this invention are to provide a fire alarm system which is reliable in operation, which indicates the location of a fire, which indicates when a fault has made the system inoperable, which is simple to install and inconspicuous or even attractive in appearance, which is economical to operate, and which generally improves the art of fire alarm construction.

In a broad aspect the invention. contemplates an alarm system, for indicating a fire in any one of a plurality of locations, comprising an indicating element and a plurality of impedance elements each of which is positioned in one of the aforementioned locations. These elements are connected with a power source in such a manner that a current is directed therebetween. The total impedance of the system and the current circulating therein can be varied by any one of a plurality of switch elements. each of which is responsive to a temperature difierential. Each of the switch members is connected with and employed to change the impedance of a respective one of said impedance elements. When, in response to a temperature differential, one of the switch members is opened, the total impedance of and thereby the current flowing in the system is varied. The registration of such variation by the indicating element gives a warning as to the existence of an abnormal temperature condition prevailing in the vicinity of the correlated impedance element.

In another aspect the invention contemplates an alarm system comprising a plurality of resistance elements, each with the same or with a different ohmic characteristic, connected in series with an indicating element and a power source for directing a current therebetween. This current can be varied by any one of a plurality of switch members each of which is responsive to a temperature differential. At a normal ambient temperature each of the switch members is used to shunt a respective one of the resistance elements. A warning is given by the registration upon the indicating element of the change in the total series resistance of the system which results from the removal of the shunt from one of the resistance elements by the respective switch member in response to a rise in temperature.

In a more specific aspect the alarm system comprises a detecting circuit including a coil of an electric meter and a plurality of resistors, each with a different ohmic characteristic, connected in series with a direct power source. Effective to shunt each of said resistors is a normally losed con act of a switch member. Each of the switch members is opened by a respective bimetallic ele ent in response to a temperature differential. The power source is used to direct a current through the detecting circuit and a plurality of auxiliary warning circuits. Each of the auxiliary circuits includes one or more signalling devices operated by the closing of a normally open contact which is an element of a respective one of the switch members. In another aspect the ener'zization of the auxiliary circuit opens a solenoid operated valve thereby turning on the sprinkler system in the adjacent area.

An increase in temperature causes the adjacent normally closed switch member to be opened by the affected bimetallic element thereby shunting one of the resistors. The change in current flowing through the system resulting from the increase in series resistance is indicated by the meter. The simultaneous closing of the normally open contact of the switch member energizes one or more signalling devices in the auxiliary warning circuit.

In still another aspect the invention contemplates the use of the pointer moved by the coil of the indicating meter or other relay to close an auxiliary warning circuit thereby energizing a signalling device from the power source when the pointer moves from its full scale position because of the decreased current flow in the system.

In another aspect the invention contemplates Fig. l is a wiring diagram of one embodiment of the invention;

' Fig. 2 is a wiring diagram of another embodiment of the invention showing one method of connecting a local alarm system;

Fig. 3 is another embodiment of the invention with another type of local alarm system;

Fig. 4 is an enlarged cross section of fire alarm-1 device;

Fig. 5 "is a cross :seotion taken on the line 5-5 oifEig. =4;

Fig; 6 shows an alternative housing vfor the switch element; and

Fig. "I is a wiring diagram of the fire alarm device.

The particular embodiment of the invention chosen for the purpose of illustration comprises, as is shown in Fig. 1, a fire alarm system for a home-having a plurality of impedance elements, such as the resistorsfl, r2, raga rheos'tat Ru and an indicating element, such as a meter M with a coil l5. These elements are connected by means of the wires ll, l2 and 13 with a power source, such as a battery B, to form a series detecting circuit. At a normal ambient temperature each of 'the resistors r is shunted by the normally closed contacts 19 and 46 of a switch S (Fig. 4). Each of the-switches S is operated by a bimetallic element b which opens the contacts 19 and 46 in response to an increase in the ambient tempera ture of the surrounding air. Each of the resistors r, with its associated switch S and bimetallic e'lement b is installed in a diiierent location; for example, in one of the various rooms of a house in which fire protection is desired.

The assembly of one of the resistors r with a switch S and a bimetallic element 1) to comprise a detecting device is shown in Fig. 4 and will be described in detail hereinafter.

With a normal ambient temperature prevailing-at each of the protected locations, all of the resistors r are shunted as described above and the current circulated through the detectingcircuit by the battery B is limited only by the resistance of the meter coil i5 and the rheostat R11. A tap H of the rheostat R11 is adjusted so that the circulating current deflects the coil [5 and an'at'tached pointer P to the full scale position of the-'meter M.

In the "full scale position, a contact carried by the'pointer P makes with a stationary contact [8, thereby connecting a, coil 22 of a relay S2 to the battery B by means of "the wires ll, 25, l0, l3 and I2. The normally closed contacts it and ll of the relay S2 are part of a supervisory circuit which also includes a manually operable switch $1, the wires 23, a signalling device such as a warning bell A, the wires 30, I3 and [2, the battery'B and the wires l l and 4.

While it is within the scope of this invention to include a detecting circuit having a plurality of resistors r with the same ohmic character-' istics, it is preferable that each of the resistors have a unique ohmic value so that the deflection of the meter pointer P can be directly correlated with the resistor r from which the shunt has been removed as described above.

A indicated by the break in the detecting circuit at x, the system is not limited to the protection of three locations, but is capable of incorporating any number of fire detecting devices. For example a six-room "house with an attic, basement and a garage would have 'a'system with nine detecting devices installed therein.

The following tabulation of preferred resistors a for use with a nine station alarm system results in equally spaced fiducial lines upon the meter scale when used with an alarm system which includes a battery B supplying 100 volt me'tercoil l5 and the resistor R1). of 10,000 ohms.

; Percentage Scale Meter Indication with 1 Resistor Shunt Removed Location of Ohmic Characteristics of Resistor 'r Resistor,

Per cent Living room... Diningroom Kitchen..-

Garage The fire detecting device ("Fig. 4) mentioned heretofore comprises a molded insulated bases! adapted to .be connected by the screws 33 to a conventional electrical connection box 32. The conduits are joined to the box 32 in the usual manner as is shown at 34 and 35. On of the re,-

sistors T which may be of the type used in electronic circuits is located in a recess 3 1 on the inner side of the base 3!. A lead 42 ('Fig. 7') at one end of the resistor, r is connected to a terminal 38a which is threaded'into a metallic strap 3.9a molded into the base 31. Also held by the conducting strap 39a is a second terminal Ma for'completing the connection ofthe resistor r in the fire alarm circuit described heretofore. The lead at the other end of the resistor r is connected to the alarm system in an analogous manner by the terminals 381) and Mb whichcngage'a strap 3%.

The switchS is of theconventional snap-acting type within a housing M which is fastened to the base 3| by the screws 43. he switch S has, in addition to the previously :mentioned normally closed contact 19 'for shunting the resistor r, a normally open contact 20 whose use willbe described hereinafter. The movable contact '46 is connected with thestrap 3% 'by means of a 'Wire 48 which is molded Within the base 3! The normally closed contact 1'9 is similarly connected to the strap 390, by a wire :45. Awire '50 connects the normally open contact 20 with a terminal 330.

The movable contact 45 of the switch S is operated by a lever 49,-one end-or" which contacts aswitch actuating pin 47, the other end being joinedwi'th the free end of the'bimetallic-element b by an adjustable screw ".56. pivoted =on a pin 5| which is supported between the projecting arms 52 of the switch housing 44.

5.. The opposite end of the bimetallic element b is fastened to one leg of an L-shaped bracket 51. The other leg of the bracket 51 is joined with the switch housing 44 by the screws 58.

The enclosure 53 for protecting the switch S and the bimetallic element b fits over a rabbet in the base 3| and is held in place by the screws 33a. The enclosure 53 is formed hemispherically from metal sheet containing a plurality of eyelets 54 pressed therein to permit ambient gases to enter while protecting the switch S and the bimetallic element b from mechanical damage.

An alternate construction of the enclosure. is shown in Fig. 6 wherein a cylindrical enclosure 53a is rolled of a foraminous sheet and fastened to the base 3| in an analogous manner.

It will be noted that in addition to decorative efiect and mechanical protection afforded the enclosures 53, these enclosures also protect the apparatus from direct contact with the flames in the event of a flre in the vicinity of the alarmdevice. Flame is prevented from entering by pro- Viding small interstices in a heat conducting material whereby in accordance with a well known principle of physics, the material cools the entering gas by conducting the heat therefrom at a rate greater than that at which heat is supplied by the gas.

In Fig. 2 is shown a second embodiment adapted to be used in a warehouse, upon a ship or in any other installation where, in addition to sounding an alarm at a central station, it is desirable, to give local warning. The detecting and. supervisory circuits are similar to those shown in the first embodiment (Fig. 1) the corresponding elements bearing the same indicia. In this second embodiment, an auxiliary warning circuit comprises a plurality of signalling devices such as the lamps L, each of which is connected in series with the normally open con- 40 tacts 20 and 46 (Fig. 4), of one of the detecting dievices.

Whenever the contacts 2!! and. 45 in one of the detecting devices are closed by the distortion of the bimetallic element b resulting from an elevated ambient temperature, the battery B is connected to an associated auxiliary warning circuit which includes one of the lamps L, the wires 2|, 24, H, [2 and I3 and the contacts l9 and 48 of the detecting devices connected between the wire l3 and the afore-mentioned detecting device being subjected to an elevated temperature.

The third embodiment shown in Fig. 3 is installed, as in a hotel, where, in addition to the alarm sounded at a central station, a general alarm must be given. In this latter embodiment changes have also been made so that the power source B of the detecting circuit is separated from a power source Ba energizing the supervisory and auxiliary warning circuits. Elements with analogous functions bear the same indicia as in the two previous embodiments.

As above, the detecting circuit comprises the coil l5 of the meter M, the rheostat Ru, and the resistors r of the detecting devices connected in series with the battery B by the wires H, [2 and I3. A service battery Ba energizes the coil 22 of the relay S2 by means of a circuit including the wires 1, 24 and It, the contact 18, the contact carried by the meter pointer P, the coil 22 and the wires 25, 30, I3 and 25. The alarm bell A in the supervisory also is connected to the battery Ba. In this embodiment the supervisory circuit includes the wires 1 and 24, the switch Sl, the contacts 16 and ll of the relay S2, the wires 39, I3 and 26 and the battery Ba.

" The general alarm circuit includes the contacts 20 and 46 of the detecting device at an elevated temperature, a plurality of signalling devices,

such as the bells Al, the wires 21, 2|, 214 and I, 5 the battery Ba, the wires 26 and I3, and the contacts l9 and 45 of the detecting devices connected between the wire l3 and the aforementioned detecting device which is subjected to an elevated temperature. It should be noted that in this embodiment, the wire 27 connects all the warning bells Al in parallel so that the closing of the contacts is and 46 in any one of the detecting devices rings all the bells Al.

An alarm system according to this invention can be easily installed by any competent electrician in a manner analogous to that in which the lighting circuits are wired. The meter M, the rheostat Rn, the battery B, the relay S2, the alarm bell A and the switch SI are grouped at any convenient central station located for example in a garage, a master bedroom of a home,

abridge of a ship, a watchmans station in a' warehouse or any other convenient strategic position.

In the first embodiment the detecting devices of the detecting circuit are joined by a cable with a single conductor connecting the successive alarm devices and the central station in the .form of a loop. A two-wire cable is used with the second embodiment with one of the wires completing the detecting circuit as described above. The second wire is the common lead of the auxiliary alarm system designated 2| in the circuit diagrams (Figs. 2 and 3). Each of the lamps L is located outside of the protected area in a corridor or in any other strategic 'position and is connected with the junction box 32 (Fig. 4) by means of a two-wire cable. In the third embodiment (Fig. 3) a three-wire cable is required, two of the wires being employed as described heretofore, the third wire 21 (Fig. 3) being used to connect the alarm bells Al in parallel.

With the switch SI open and the battery 13 connected, the alarm system is placed in operation by adjusting the rheostat Rv so that, with all the detecting devices at a normal ambient temperature and the resistors 1 therein shunted through the switches S, a current sufl'icient to deflect the pointer P to full scale flows through the detecting circuit including the battery B, the wire H, the rheostat Re, the coil [5, the contacts l9 and 48 of the switches S, the wires I3 and 12. In this position the pointer contact makes with the contact I 8 to energize the coil 22 of the relay S2 by means of the battery B through a circuit completed by the wires I0, [3, I2, I I and 25 in the embodiments shown in Figs. 1 and 2; or to the battery Ba by a circuit completed by the wires I0, 24, I, 26, I3 and in the embodiment shown in Fig. 3. The manually operated switch SI is then closed and the alarm system is ready.

In case of fire in one of the protected locations the elevated ambient temperature distorts the bimetallic strip at b in the adjacent detecting device thereby to open the associated contacts l9 and 46 and remove the shunt from the associated resistor r. The resulting increase in the total series resistance of the detecting circuit decreases the current flow which is reflected by a lesser deflection of the meter pointer P. As eachof the resistors R is of different ohmic characteristic the deflection of the pointer P can be directly correlated with the location of the de- 76 tecting device.

When, as idescribed above, the pointer-P moves from the full scale position the contact 18 open's to deenergize the coil 22 of the relay -s2 so that the normally closed contacts l6 and H make and ring the alarm bell A. v. &s*any"increase in the detecting circuit resistance sounds an alarm the alarm system is self-supervising. 1Abreak in any of leads of the detecting circuit will make the circuit resistance infinite thereby to deenergize the coil [5. The meter j'pointer P returns to zero and the alarm bell A is sounded as described heretofore.

In the embodiment shown ilLFig. .2 the =distortion of the bimetallic element 1) of one of the detecting devices by an elevated ambient temperature also closes the contacts '46 and .20 ;to light the local lamp L from the battery '13 by energizing the auxiliary warning :circuit including the wires 21, 24, ll, 12 and and the shunting contacts l9 and dbof the detecting-devices located between the "wire .13 and the aforementionedzdetecting. device which :is subjected to an elevated temperature.

The auxiliary warning circuitin the embodi merit shown :in Fig. 3 is energized in an analogous manner by the 'closing of contacts :and '46 of any one of the detecting devices which is subjected to'an elevated temperature. Because of the lead '21 all of the bells AI were energized by battery Ba to sound a general alarm through a "circuit including "the contacts 20 and 46, the wires '21, 2|, 24, 1, 261and l3 and the shunting contacts I19 and '46 of the detecting devices located between the"wire 1-3 and the aforementioned detecting device which :is subjected to 1 an elevated temperature.

'It should be understood that the present disclosure "is for the purpose of illustration only and "that this invention includes all modifications and equivalents which fall Within the scope of the appended claim.

I claim:

In an alarm system for selectively indicating a fire in -any :one of a plurality :of locations '2. detecting :circuit comprising an electric meter with a coil-and a pointer moved by said 'coil,.'a

plurality ofwreslstors each of which .:has a dif-' ferent ohmic characteristic and each of which is located in 'a respective one of :said location's, a direct power source connected in :series 'with the meter coil and said resistors a plurality 'of switch members each with a norm-ally opened contact and-a normally closed contactior shunting a respective one of said resistors, a plurality of bimetallic elements "for operating each a respective one of said switches in response to a temperature differential; :and a plurality of auxiliary warning circuits each with a signalling device connected'with said power source by the operation of a respective one of said normally opened contacts whereby the meter pointer indicates the change in current flowing in the :system resulting from "the increase vin the total series resistance of the system by the opening o'f'any one of the normally closed contacts the signalling device is operated upon the "completion of an auxiliary warning circuit by the closing of a normally opened contact :by the -opstation of one o'f said switch members by the associated bimetallic elements in response to 'a rise in ambient temperature.

JOSEPH D. 'CONSTANTINO.

. REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 245,272 Bright Aug. '39, 1881 758,819 'Callum May '3, 1904' 1,954,832 Ruben Apr. 17,1934

2,000,074 Grant May '7; 1935 2,003,443 'Henne'berger June '4, 1935 2,165,569 Obermaier July 1'1, 1939 2,219,262 Mample Oct. 22, 1940 2,408,660 Lannge Oct. 1, 1946 2,423,649 Horvitch July 8, I947 2,450,450 Schmidinger Oct. 5, 1948 2,452,942 Lord et a1. 'NovI'Z, I948 

